Rory McIlroy says his biggest challenge this year was winning girlfriend back

Rory McIlroy may have impressed millions when he won the U.S. Open, but he says his biggest challenge this year was winning back girlfriend Holly Sweeney.

According to the Daily Mail, the 22-year-old has revealed the "begging and groveling" he had to do after breaking up with his sweetheart last year.

"At the start of the year I wanted to take a break and just focus on my game," he told BBC Northern Ireland in a documentary entitled 'Rory's Major Breakthrough.'

"But I realized pretty quickly I had made a huge mistake, and I had to do a lot of begging and grovelling to get her back. Holly is fantastic. I have known her for six years and for someone my age that is a huge chunk of my life. She keeps my feet on the ground and knows the things to say to me. She has been such a great support. She takes my mind off golf and everything else that is going on."

In the documentary, the 20-year-old Holly, a sports technology student, recalls first meeting McIlroy in 2005.

"I was up at the course at Holywood caddying with a couple of the girls and he was practicing," she said. "Rory came over and said hello and that was how it started."

"I didn't even know who he was at that stage. He is still the same guy. Not one thing about him has changed. Being a champion doesn't come into it. You have to keep him grounded and say and do the things we always do, like going to the cinema or Tesco's."